JPH07273066A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a semiconductor device having a silicide film which has a low contact resistance and high heat-resistant properties on a shallow diffused layer. CONSTITUTION:After a transition metal film such as a Ti film 17 is formed on the surface of a semiconductor substrate 11, a Ti target is sputtered by a nitrogen plasma to form a TiN film 8. With this constitution, the Ti film 17 is protected from the invasion of nitrogen and a sharp nitrogen composition profile is provided in the boundary of the Ti/TiN films.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device in which a transition metal compound film is formed on a shallow impurity diffusion layer.

[0002]

2. Description of the Related Art In recent years, with the high integration of semiconductor devices, miniaturization of electric circuits has been progressing, and miniaturization of field effect transistors (FETs) and the like, which are basic elements, is also required. In order to suppress the occurrence of the short channel effect as the width of the gate electrode of the FET is narrowed, it is required to make the diffusion layer depth of the source and drain regions shallow, and the low acceleration ion implantation method is widely used. ing. By using this method, a shallow source / drain region of 0.1 μm or less can be formed, and it is possible to improve the performance as the FET is miniaturized. In this case, the resistance of the impurity diffusion layer is high and 1 × 10 5. -Sheet resistivity of ^-5 Ωm or more. In order to increase the speed of the semiconductor device, it is necessary to reduce the sheet resistance of the diffusion layer so that the drain current can easily flow. For this purpose, as an example, a method of metalizing the surface of the diffusion layer to reduce the resistance has been proposed, and one of such methods is a method called salicide, in which the surface of the diffusion layer is silicided in a self-aligned manner. is there.

A method of manufacturing a MOSFET using this salicide will be described below with reference to FIG. . First,
An impurity diffusion layer is formed by a well-known ion implantation method on a substrate having a structure in which a silicon surface is exposed by being surrounded by a 150 nm SiN film 3e formed on the sidewalls of the field oxide film 2 and the gate electrode 3. Then, the surface of the titanium target is sputtered with plasma of argon (Ar) gas to deposit a titanium (Ti) film 7 with a thickness of 40 nm. Next, the surface of the titanium target is treated with nitrogen (N ₂ ) and A
Sputtering is performed by plasma generated by a mixed gas of r, and titanium nitride (Ti
While forming N), the TiN film 8 is deposited on the surface of the Ti film 7 (FIG. 7A).

Subsequently, a heat treatment is performed in a nitrogen atmosphere to form a titanium silicide (TiSi ₂ ) film 9 (FIG. 7).
(B)). After that, unreacted Ti and TiN are removed by etching using a mixed solution of sulfuric acid and hydrogen peroxide (FIG. 7C). By the steps up to this point, TiSi ₂ is self-aligned only on the impurity diffusion layer. The film 9 is formed. Finally insulating film 1
0 is provided to open a contact hole, and then electrode wiring 11
Are formed (FIG. 7D).

According to this method, for example, a sheet resistance of about 2.9 is formed by forming a silicide of 80 nm.
It can be reduced to × 10 ⁻⁷ Ωm. Here, the TiN film deposited on the surface of the Ti film 7 was used as a cap material to suppress oxidation of the surface of the Ti film and was an essential film for forming a good TiSi ₂ film. However, recent MOS
It has been found that the following problems occur due to research on further miniaturization of FETs.

Since the silicide is formed directly on the diffusion layer, the formation of the silicide consumes the substrate Si and reduces the effective thickness of the diffusion layer. For example, 0.1μ
When a TiSi ₂ film having a thickness of 80 nm is formed after the diffusion layer having a thickness of m is formed, the remaining thickness of the diffusion layer becomes as small as 20 nm. It was clarified that the junction leakage current of the diffusion layer increases remarkably as the effective diffusion layer thickness decreases. Therefore, in order to avoid this problem, it has become important to reduce the thickness of silicide. However, as a result of further studies, it became clear that the following problems would occur.

That is, if the thickness of the deposited Ti film is reduced in order to reduce the thickness of the TiSi ₂ film to be formed, Ti is reduced.
It was revealed that the resistivity of the Si ₂ film increased, and the sheet resistance of the diffusion layer did not decrease as initially expected. Therefore, it is necessary to increase the thickness of the deposited Ti film and increase the thickness of the TiSi ₂ film in order to fully exhibit the performance of the device, which is a factor that hinders the improvement of the performance of the device. For example, TiSi ₂ having a film thickness of 50 nm is formed by the above method.
When formed to have a thickness of 30 nm, for example, the specific resistance of the TiSi ₂ film becomes 25 μΩcm. The ideal resistivity of the TiSi ₂ film is around 13 μΩcm, which is 90% of that.
Was too high, the sheet resistance could not be sufficiently reduced.

Further, when this film was heat-treated, 750 ° C.
Since a phenomenon in which the sheet resistance sharply rises in the above temperature range, a detailed examination of the state of the film revealed that a so-called agglomeration phenomenon, in which crystal grains of the TiSi ₂ film aggregate due to heat treatment, has occurred. It was revealed.
It has been previously reported that agglomeration remarkably occurs at 900 ° C. or higher, but no report has been made at such a low temperature, and it is clear that this is a serious problem that suppresses device miniaturization. It's coming. Therefore, there is an urgent need to elucidate these causes and take countermeasures against them.

[0009]

As described above, when the TiSi ₂ film is formed on the following shallow junction in a self-aligned manner, it is necessary to reduce the thickness of the TiSi ₂ film in order to prevent the occurrence of junction leak. was there. However, it has been revealed that when the TiSi ₂ film is thinned, the specific resistance of the film is increased and at the same time, the heat resistance against agglomeration is remarkably reduced, so that it is difficult to further miniaturize the device.

The present invention has been made in view of the above problems,
An object of the present invention is to provide a method of manufacturing a semiconductor device having a transition metal compound film having a low specific resistance and high heat resistance even when a transition metal compound such as TiSi ₂ is thinned to a thickness of 50 nm or less. .

[0011]

The present invention has been made in order to achieve the above object, and employs the following configurations. That is, the present invention provides a step of forming a first film made of a transition metal on the surface of a semiconductor substrate, and a second step of making a compound of the transition metal and the second periodic element of the periodic table on the surface of the first film. Forming a film containing the second periodic element larger than the normal composition in a region in contact with the first film, and forming the film on the surface of the semiconductor substrate by heat treatment and the first element. Forming a third film made of a compound of the above film with a transition metal.

Here, the following are preferable examples of the present invention. (1) The second film is formed by containing the second periodic element in an amount less than the regular composition on the surface side of a region in which the second periodic element is included in an amount larger than the regular composition.

(2) The second film is formed by including the second periodic element in a regular composition on the surface thereof. (3) The composition obtained by averaging the inside of the second film is a normal composition.

(4) In the step of forming the second film, the transition metal of the second film is formed in an atmosphere of a gas containing the second periodic element as a main component at an initial stage of film formation. -By sputtering the get.

(5) In the step of forming the second film, after the initial stage of the film formation, in an atmosphere of gas containing a smaller amount of the second periodic element than in the initial stage of the film formation,
This is performed by sputtering a target made of the transition metal of the second film.

Further, according to the present invention, a first film made of a transition metal is sputtered on the surface of a semiconductor substrate, and a target made of the transition metal is sputtered in an atmosphere of an inert gas inert to the transition metal. And a second film formed of a compound of a transition metal and a second periodic element of the periodic table on the surface of the first film, a gas containing the second periodic element, and Sputtering a target made of the transition metal of the second film in an atmosphere of a mixed gas having a low first ionization energy and an inert gas inert to the transition metal of the first film. And a step of forming a third film made of a compound of a constituent element of the semiconductor substrate and a transition metal of the first film on the surface of the semiconductor substrate by heat treatment. Do

Here, the gas containing the second period element is N _2, which has a first ionization energy higher than that of this gas.
It is preferable that the inert gas having a low content ratio is made of at least one of xenon and krypton.

Further, the preferred embodiments of the present invention described above include the following. (1) After forming an insulating film in a desired pattern on the semiconductor substrate, forming the first and second films on the semiconductor substrate, and the surface of the semiconductor substrate other than the region where the insulating film is formed. And forming the third film in a self-aligned manner by heat treatment.

(2) An impurity diffusion layer is formed on the surface of the semiconductor substrate, and the third film is formed on the surface of the semiconductor substrate on which the impurity diffusion layer is formed. (3) The second periodic element is B, C, N or O 1
Must be one or more types of elements.

(4) The transition metal of the first and second films is Ti. (5) The third film is made of a transition metal silicide and has a film thickness of 50 nm or less.

[0021]

As described above, when a film made of a transition metal is formed on the surface of a semiconductor substrate and a film made of a compound of the transition metal and a constituent element of the semiconductor substrate is formed by heat treatment, When the film made of a compound is thinned to form a film made of the above compound, the specific resistance of the film becomes high and the heat resistance to agglomeration decreases.

As a result of intensive studies, the present inventors have found that this phenomenon is caused by the following. That is, when forming a film made of a compound of a transition metal and a second periodic element, for example nitrogen, on the surface of the film made of the transition metal as a cap material, the film made of this compound is used as a gas containing the second periodic element. When it is formed by using, a plasma species composed of an active second period element is generated, and this plasma species penetrates into the surface region of the film composed of the transition metal. This invading plasma species forms a defect layer or the like in which impurities such as nitrogen and oxygen are easily mixed in the invading surface region, whereby a film made of the compound of the transition metal and the second period element and the transition metal are formed. The interface with the film made of is unclear.

Due to such ambiguity at the film interface, when a film made of the compound of the transition metal and the constituent element of the semiconductor substrate is formed by the subsequent heat treatment, the film thickness becomes uneven, It has been found that a region where the second periodic element remains is formed on the surface of the film, and as a result, the specific resistance of the film and the heat resistance to agglomeration deteriorate.

According to the present invention, the plasma species of the gas containing the second periodic element, the plasma species of the second periodic element is formed in a low activity state, and the active plasma species of the transition metal is the surface of the film. By preventing entry into the region, a film (third film) made of a compound of a transition metal and a constituent element of the semiconductor substrate formed by heat treatment has a uniform film thickness, and the film surface has the above-mentioned first film. It is possible to suppress the formation of a region where the two-period element remains. As a result, it is possible to improve the specific resistance of the film and the heat resistance to agglomeration.

According to the present inventors, as described above, the second
When a plasma species composed of a periodic element is formed in a state of low activity, a film composed of the transition metal (first film)
In the interface region in contact with the film (second film) made of the compound of the transition metal and the second period element, the second ratio element has a composition ratio higher than the normal composition ratio.
It was found that the film of No. 1 should be formed.

For example, in order to form a plasma species having a low activity, the second film is formed in an atmosphere of a gas containing the second periodic element as a main component in the initial stage of forming the second film. When the second film is formed by sputtering a transition metal target, in the interface region of the first film in contact with the second film, the composition ratio of the second periodic element is higher than the normal composition ratio. It was found that the second film should be formed so that

[0027]

EXAMPLES The details of the present invention will be described below with reference to examples. FIG. 1 shows a first method of manufacturing a semiconductor device according to the present invention.
FIG. 6 is a process sectional view for explaining the example of FIG.

This embodiment shows an example of manufacturing a MOSFET. First, an 800 nm field oxide film 12 is formed by an embedding method on an n-type silicon substrate 11 whose main surface is (001). In the element region surrounded by this oxide film, an oxide film (not shown) having a film thickness of 10 nm, an impurity-doped polycrystalline silicon layer having a thickness of 150 nm, and a thickness of 150 nm
Of tungsten silicide (WSi ₂ ) layers of
These are etched to form a gate oxide film 13a, a polycrystalline film 13b, and a WSi ₂ film 13c. Then, a silicon nitride (SiN) film (not shown) is deposited to a thickness of 150 nm and processed by anisotropic etching to form a SiN film 13e on the side wall of the gate portion 13. Next, S of 10 nm
The io ₂ films 16 and 13d are formed on the exposed Si surface by thermal oxidation, and BF ²⁺ ions are applied at 35 keV and 5 × 10 ¹⁵ cm ^−2.
After pouring, in a N ₂ atmosphere RTA (Rapid Th
The shallow p ⁺ diffusion layer 14 having a thickness of about 0.1 μm is formed by performing a heat treatment at 1000 ° C. for 20 seconds by the thermal anneal method (FIG. 1A).

Thereafter, the surface of the p ⁺ diffusion layer is treated with a mixed solution of sulfuric acid and hydrogen peroxide to treat the surface contamination of the carbon (C) type, and then the contamination of the metal type is treated with the mixed solution of hydrochloric acid and hydrogen peroxide. . Then thin SiO formed on the surface of the p ⁺ diffusion layer
Dissolved oxygen concentration is 10 ppb after cleaning and peeling ₂ films with diluted hydrofluoric acid.
Wash with running water using the following ultrapure water.

Next, using a sputtering apparatus as shown in FIG. 2 (a), the substrate 11 on which the p ⁺ diffusion layer 14 has been formed as described above and the Ti target 20 are arranged facing each other, and Ti
By sputtering the surface of the target 20 with Ar plasma, a Ti film 17 having a thickness of 24 nm is deposited on the surface of the p ⁺ diffusion layer as shown in FIG.

Then, using a sputtering apparatus as shown in FIG. 2B, a flow rate of 40 sccm is set in the sputtering chamber.
The Ti target 20 is sputtered by plasma generated by N ₂ gas introduced with a certain degree. As a result, a TiN film 18 of about 100 nm is deposited on the surface of the Ti film 17 so that nitrogen is contained in an amount higher than the normal composition ratio while forming a titanium nitride (TiN) by nitriding reaction on the Ti target surface 20. Let Substrate 11 is about 10
Heat to 0-300 ° C. Then, the Ti target 20 is sputtered by continuously adjusting the partial pressure ratio of the Ar gas and the N ₂ gas.
The N film 18 is deposited. As an example of adjusting the stoichiometric composition ratio, the flow rate of Ar is set to about 20 sccm and the flow rate of N ₂ is set to about 20 sccm. Furthermore, the gas pressure is 10 ⁻³ to 10 ⁻⁴ Tor during each process.
It is set in the range of r (FIG. 1 (b)).

In the above-mentioned sputtering process, the substrate 11 to be processed is placed in a state of being floated from the ground potential or a potential close to the plasma potential used in sputtering.

After that, the Ti film 17 and the TiN film 18 are annealed in a nitrogen atmosphere to form a TiSi ₂ film 19, and the TiN film 18 and the unreacted Ti film 17 are removed by etching (FIG. 1C). .

Subsequently, after forming the interlayer insulating film 10, T
A contact hole leading to the iSi ₂ film 19 is opened, and a wiring 100 for a source / drain electrode is formed to complete a MOSFET by the manufacturing method of this embodiment (FIG. 1).
(D)).

When the TiSi ₂ film 19 formed by the above method was evaluated, the specific resistance was 16 μΩcm, which was a low value equivalent to an ideal value, although the TiSi ₂ film 19 had a very thin film thickness of about 30 nm. It became clear that As a result, the sheet resistivity was 3 × 10 ⁻⁷ Ωm when a 30 nm TiSi ₂ film was formed by the conventional method, while it was 1.5 × 10 ⁻⁷ Ωm when the above method was used. About 1/2
It has become possible to reduce to.

Furthermore, regarding the sheet resistivity of the TiSi ₂ film 19 heat-treated at a temperature of 700 to 900 ° C., no increase in sheet resistance was observed in all temperature ranges. Here, in the case of using the conventional technique, the resistance suddenly increases from the point of exceeding 750 ° C., and the film thickness is 30 nm at 900 ° C.
The film had a high resistivity of 9 × 10 ⁻⁶ Ωm or more.
That is, when a TiSi ₂ film having a thickness of 50 nm or less is formed,
According to the method of the present embodiment, it has been revealed that a low resistivity equivalent to an ideal value can be realized, and at the same time, a TiSi ₂ film 19 having high heat resistance that does not cause aggregation up to a high temperature of 900 ° C. can be formed. .

In order to clarify the above mechanism,
The interface immediately after the deposition of the Ti film 17 / TiN film 18 and the interface of the TiSi ₂ film 19 / TiN film 18 after the heat treatment formed in the above-described examples were observed by a cross-sectional TEM. As a result, at the interface using the conventional technique, the interface of the TiN film 18 / Ti film 17 was already unclear at the time of depositing the TiN film 18, and nitrogen infiltration was observed on the Ti film 17 side. A region containing a high concentration of nitrogen was formed on the surface of the TiSi2 film 19 formed by the heat treatment.

On the other hand, the T formed by the method of the present invention.
Interface between i film 17 / TiN film 18 and TiS after heat treatment
The interface between the i ₂ film 19 and the TiN film 18 was very clear. FIG. 3A shows the Ti film 17 / TiN film 18 immediately after deposition.
FIG. 9 is a profile diagram of the composition immediately after deposition, showing the Ti film 17 /
It can be seen that the nitrogen composition at the interface of the TiN film 18 is formed steeply.

The surface roughness of the TiSi ₂ film formed by the conventional method is about 3 to 10 nm, while the surface roughness of the TiSi ₂ film 19 obtained by the method of this embodiment is about 2 nm.
It was found to be suppressed to -5 nm or less, and the surface morphology was improved.

Furthermore, a sectional TEM (Transmi
ssion Electron Microscop
e) Observation, XRD (X-Ray Diffratio)
n) According to the result of the measurement, according to the method of this embodiment, T
No significant difference was observed in the crystal grain size and phase of the iSi ₂ film 19. That is, in the case of forming the TiSi ₂ film by conventional methods, nitrogen penetrates into the Ti film side during the TiN film deposition, the nitrogen concentration in the TiN / Ti film interface uneven region is formed, Therefore TiSi ₂ film Base Si during formation
The non-uniform supply was caused, and local unevenness was generated on the surface of the TiSi ₂ film. The local irregularities easily cause aggregation and also increase the specific resistance when the thickness of the TiSi ₂ film is around 30 nm. According to the method of this embodiment, T
A steep TiN film 18 / Ti film 17 interface can be formed during the deposition of the iN film 18, and the Ti film 1 can be formed during the deposition of the TiN film 18.
Since there is no invasion of nitrogen into the 7 side, it is considered that the above factors could be eliminated, and that a good film having no grain boundary and no phase difference could be obtained.

As a result of further consideration of this mechanism, the following facts have become clear. That is, in the conventional method, T
for the i target sputtering by plasma of a mixed gas of N ₂ and Ar, higher than the first ionization energy of N _2, N ₂ is excessively activated by high ionization efficiency Ar. As a result, the plasma density is increased, and the Ti film that has already been deposited is exposed to the active and high-density plasma.
A nitrogen intrusion region is formed on the Ti film side of the film interface, and TiN /
The Ti film interface was obscured.

The first ionization energy of Ar and N ₂
The difference in the first ionization energy of 1 increased the kinetic energy of the plasma species of nitrogen, and similarly promoted the invasion of nitrogen to the Ti film side.

Further, it is considered that when the nitrogen partial pressure becomes low, the mean free path of the plasma species of nitrogen in the plasma becomes long, the probability of reaching the substrate surface becomes high, and the frequency of nitrogen intrusion also increases.

The area where nitrogen penetrates by these processes is Ti
In forming by heat treatment the Si ₂ film, cause uneven silicidation results in localized irregularities on TiSi ₂ film surface, the nitrogen is incorporated into TiSi ₂ film surface.

On the other hand, in the method of the present embodiment, the Ti film is first formed by using plasma of nitrogen gas, which has a lower density, less active nitrogen, and lower kinetic energy than the conventional method. The formation of a nitrogen invasion region on the surface of 17 is prevented, and the Ti film 17 / TiN film 1 is formed.
8 interfaces can be formed steeply. Further after this, FIG.
As shown in FIG. 3, since TiN having a desired film thickness and a stoichiometric composition ratio is continuously deposited on the previously deposited N ₂ excess TiN film, excess nitrogen in the TiN film is reduced to T
Inward diffusion to the i film 17 side can be suppressed to the minimum.

In order to improve the surface morphology of the TiSi ₂ film, first, it is necessary to prevent nitrogen from entering the Ti film side during sputtering and form the Ti / TiN interface sharply.
Secondly, it is important to prevent the inward diffusion of excess nitrogen from the TiN film. However, when a TiN film is formed by sputtering with plasma generated by using a gas containing N ₂ on the Ti target surface, when Ar is used as a gas that does not react with Ti, it is active because of the reason described above. Nitrogen penetrates into the Ti film. In this embodiment, T
After the i film 17 is deposited, the TiN film 18 is deposited without using Ar at the initial stage of deposition to form a steep interface in a state where the nitrogen composition ratio is higher than the stoichiometric composition ratio, Further, a TiN film 18 having a stoichiometric composition ratio was continuously deposited. This method solves the above-mentioned problems. Further, when the Ti film 17 / TiN film 18 is deposited, the Ti film 1
The area where nitrogen penetrates into 7 is not formed, and the reduction of the effective film thickness of the Ti film 17 can be prevented, and a uniform thin film TiSi ₂
19 can be obtained with a desired film thickness with good reproducibility. Therefore, it is considered that the specific resistance can be reduced and the sheet resistivity on the surface of the diffusion layer can be reduced.

Next, a second embodiment of the present invention will be described with reference to FIG. First, an 800 nm field oxide film 42 is formed by an embedding method on an n-type silicon substrate 41 whose main surface is (001). An oxide film (not shown) having a film thickness of 10 nm, a polycrystalline silicon layer containing impurities of 150 nm, and a tungsten silicide (WSi ₂ ) layer of 150 nm (not shown) are sequentially deposited in the element region surrounded by the oxide film, and then these gate shapes are formed. Then, the gate portion 43 is provided by etching.
Then, a SiN film is deposited to a thickness of 150 nm and processed by anisotropic etching to form a SiN film 43e on the side wall of the gate. Next, a 10 nm SiO ₂ film 46, 43d is formed on the S
After forming on the exposed surface, BF ²⁺ ions are added at 35 keV
5 × 10 ¹⁵ cm ^-2 at 1000 ° C in N ₂ atmosphere
A shallow p ⁺ diffusion layer 44 of about 0.1 μm was formed by applying a heat treatment for 20 seconds (FIG. 4A).

After that, the surface of the p ⁺ diffusion layer 44 is treated with a mixed solution of sulfuric acid and hydrogen peroxide to treat carbon (C) -based surface contamination, and then the metallic contamination is treated with a mixed solution of hydrochloric acid and hydrogen peroxide. To do. Furthermore, a thin S formed on the surface of the p ⁺ diffusion layer 44
After removing the iO ₂ film by washing with diluted hydrofluoric acid, the dissolved oxygen concentration is 10p
Wash with running water with ultrapure water of pb or less.

Then, using the sputtering apparatus as shown in FIG. 2A, the substrate 41 to be treated and the substrate to be processed T were used in the same manner as in the first embodiment.
The i target 20 is arranged oppositely, and the Ti target surface is sputtered with plasma generated by Ar gas to deposit a 18 nm-thick Ti film 47 on the surface of the p ⁺ diffusion layer 44.

Then, using a sputtering apparatus as shown in FIG. 2B, N ₂ gas having a flow rate of about 40 sccm was introduced into the sputtering chamber to generate plasma, and the plasma was applied to the surface of the Ti target 20. By sputtering with plasma, TiN is formed by the nitriding reaction on the surface of the Ti target 20, while the Ti film 47 is formed.
A first TiN film 48a having a film thickness of about 10 nm is deposited on the surface of the.

Then, the sputtering apparatus of FIG. 2 (b) is continuously used to perform Ti by plasma with a mixed gas of N ₂ and Ar.
By sputtering the target, a second TiN film 48b is formed on the surface of the first TiN film 48a by about 5 times.
Deposit to a thickness of nm. This mixed gas has a flow rate of N ₂ of 1 to 14 s so that the composition of nitrogen is less than the normal composition.
The flow rate of Ar is adjusted to be 40 sccm together with the flow rate of N ₂ within a range of ccm.

Similarly, the surface of the Ti target 20 is formed on the surface of the TiN formed by using the sputtering apparatus of FIG.
Sputtering was performed by plasma with a mixed gas of N ₂ and Ar whose flow rates were both adjusted to 200 sccm so that the film composition had a stoichiometric composition ratio of 1: 1 and a nitriding reaction was caused on the surface of the Ti target 20 to form TiN. However, the third TiN film 48c is formed on the surface of the second TiN film 48b by about 6 times.
Deposit to a thickness of 0 nm.

The pressure in the chamber is 10 ^-3 to 1
It is set to 0 ⁻⁴ Torr (FIG. 4B). Here, in these sputtering steps, the substrate 41 to be processed is placed in a state of being floated from the ground potential or set to a positive potential so as to be a potential close to the plasma potential used in sputtering.

Next, heat treatment is performed in an N ₂ atmosphere at 750 ° C. for 30 minutes to form a TiSi ₂ film 49, and then T
iN films 48a, b, c and unreacted Ti 47 are removed,
Similar to the first embodiment, the interlayer insulating film and the wiring for the source / drain electrodes are formed, and the MOS according to the manufacturing method of the present embodiment is formed.
The FET is completed.

TiSi ₂ film 49 formed by the above method
Was evaluated, the TiSi ₂ film 49 had a thickness of about 30 nm.
Although it was extremely thin, it was revealed that the specific resistance was 16 μΩcm, which was a low value equivalent to the ideal value, as in the first embodiment.

In this embodiment, as in the first embodiment, N ₂
By sputtering with plasma created by only gas, nitrogen plasma having a lower density and less active nitrogen than the conventional method is used, nitrogen is prevented from entering the surface of the Ti film 47, and a Ti / TiN film interface is formed. Can be clearly formed. Further, by heating the TiN 48a when it is deposited, the excess nitrogen that enters the Ti film 47 is desorbed.
Excess nitrogen in the TiN film 48 during the silicidation is T
Inward diffusion to the i film 47 side can be prevented to a minimum.
As a result, it is possible to prevent the effective reduction of the thickness of the Ti film 47 during the TiN film 48 is deposited and silicidation at, with the resulting thickness of the desired TiSi ₂ film 49, the surface of the TiSi ₂ film 49 Good morphology.
Further, as a result of nitrogen invading into the Ti film, impurity nitrogen on the surface of the TiSi ₂ film, a TiN grain, and a region having many defects that did not exist conventionally do not occur, so that oxygen is not mixed into such a region or oxidation occurs. Since this can be prevented, the specific resistance of the TiSi ₂ film can be reduced and the heat resistance can be improved.

Further, it was confirmed that the starting temperature of aggregation is improved by 50 ° C. or more as compared with the prior art as in the case of the first embodiment. Thus, according to the method of the second embodiment, S
The mechanism by which a good TiSi ₂ film 49 can be formed on the surface of the i substrate 41 can be explained as follows.

As the first mechanism, the second TiN film 48b for diffusing the excess nitrogen existing in the first TiN film 48a used as the cap material to the outside is used as the first TiN film 4a.
It is because nitrogen is prevented from inwardly diffusing into the Ti film 47 by being formed continuously in 8a.

That is, TiN / T is formed by performing sputtering with N ₂ gas only at the initial stage of depositing the TiN film 48.
A surplus nitrogen region is formed at the interface of the i film, and this interface is formed steeply. As a result, the diffusion of nitrogen to the Ti film side may become a problem. However, as shown in FIG.
Immediately above the N film 48a, Ti having a higher Ti composition than the normal composition
By depositing the N film 48b, a layer for outwardly diffusing the excess nitrogen in the TiN film 48a is positively formed, and the inward diffusion of nitrogen to the Ti film 47 deposited on the Si substrate can be reduced. Therefore, it is possible to prevent the Ti film thickness from decreasing.

As a second mechanism, as in the case of the first embodiment, when the first TiN film 48a is deposited, active nitrogen is prevented from entering the inside of the Ti film 47, and the TiN film 48 is prevented.
Since the surplus nitrogen region is formed on the first TiN film 48a side of the a / Ti film 47 interface, the TiN film 48a / Ti film 47 interface is to be made clear. As a result, TiSi ₂
By preventing the surface morphology of the film 49 from becoming rough and by preventing nitrogen from being partly taken into the surface of the TiSi ₂ film 49, the start temperature of aggregation can be improved,
Further, the specific resistance can be reduced and the sheet resistance on the surface of the diffusion layer can be reduced.

Furthermore, by sputtering without generating active nitrogen having energy, the bonds near the surface of Ti are not broken, lattice defects are not generated, and Ti film 47 / TiN at the time of the subsequent heat treatment. It suppresses uneven nitriding and excessive incorporation of nitrogen at the interface of the film 48a. here,
Nitrogen taken into the TiSi ₂ film 49 has an atomic radius of 1.71 A (angstrom) and Ti (0.68 A).
A) and Si (0.41A), so Ti
It is introduced into the inter-lattice or lattice defects of the Si ₂ film 49 to introduce local strain and increase the electron diffusion resistance. This is due to two factors, namely, the scattering cross section simply increases due to the large atomic radius of N, and the periodic potential of the lattice of the TiSi ₂ film is distorted. Where T
When iN is distributed in the TiSi ₂ film, it has the same effect as nitrogen. Here, the first TiN film 48a
FIG. 3 shows the relationship between the composition and film thickness of the second TiN film 48b and the second TiN film 48b.
As shown in (b), the excess nitrogen (1) in the first TiN film 48a can be consumed by the excess Ti (2) of the second TiN film 48b, that is, the excess nitrogen TiN film 48a and the excess TiN film 48a. The average composition of the TiN film 48b is formed to match the normal composition.

Further, a third embodiment of the present invention will be described with reference to FIG. First, an 800 nm field oxide film 42 is formed by an embedding method on an n-type silicon substrate 41 whose main surface is (001). In the element region surrounded by the oxide film 42, 10 nm gate oxide films 43a and 150n are formed.
A gate portion 13 composed of a doped polycrystalline silicon film 43b of m and a tungsten silicide (WSi ₂ ) film 43c of 150 nm is formed. After that, a SiN film is deposited to a thickness of 150 nm and processed by anisotropic etching to form the gate portion 1.
A SiN film 43e is formed on the side wall of No. 3. Then 10 nm
After forming the SiO ₂ film 46 of BF ₂₊ on the exposed surface of Si,
Ions were implanted at 35 keV at 5 × 10 ¹⁵ cm ^-2 and heat-treated at 1000 ° C. for 20 seconds in an N ₂ atmosphere to form a shallow p ⁺ diffusion layer 44 of about 0.1 μm (FIG. 1).
(A)).

After that, the surface of the p ⁺ diffusion layer 44 is treated with carbon (C) based surface contamination with a mixed solution of sulfuric acid and hydrogen peroxide, and then metal based contamination is treated with a mixed solution of hydrochloric acid and hydrogen peroxide. To process. Thereafter, the thin SiO ₂ film formed on the surface of the p ⁺ diffusion layer 44 is washed and stripped with dilute hydrofluoric acid, and then washed with running pure water having a dissolved oxygen concentration of 10 ppb or less.

Next, using a sputtering apparatus as shown in FIG. 2A, the substrate 41 to be processed and the Ti target 20 are arranged facing each other, and the surface of the Ti target 20 is 30 to 45 sccc.
As shown in FIG. 4B, a Ti film 47 having a thickness of 18 nm is deposited on the surface of the p ⁺ diffusion layer 44 by sputtering the plasma generated with Ar gas in the range of m. Then, using a sputtering apparatus as shown in FIG.
The surface of the i target 20 is filled with N ₂ gas, for example, 40 sccm.
The Ti target 2 by introducing it into the sputtering chamber and sputtering it with the newly formed plasma.
While forming TiN by the nitriding reaction on the 0 surface,
First, a first TiN film 48a is formed on the surface of the i film 47 by about 10n.
It is deposited to a thickness of m (FIG. 4 (b)).

Next, again using a sputtering apparatus as shown in FIG. 2A, Ar in the range of 30 to 45 sccm is used.
By sputtering the Ti target 20 with gas plasma, a second TiN film 48a is formed on the surface of the first TiN film 48a.
A Ti film 48b 'is deposited to a thickness of about 5 nm.

Finally, the flow rate is adjusted to about 20 sccm on the surface of the Ti target 20 by using the sputtering apparatus of FIG. 2B so that the composition of the TiN film to be formed has a stoichiometric composition ratio of 1: 1. By sputtering with plasma using a mixed gas of N ₂ and Ar
While forming TiN by the nitriding reaction on the surface of the target 20, the TiN film 48c is formed on the surface of the second TiN film 48b.
Is deposited to a thickness of about 60 nm (FIG. 4 (b)). In these sputtering steps, the pressure applied to the mixed gas is 1
The substrate 41 to be processed has a range of 0 ⁻³ to 10 ⁻⁴ Torr.
It is set so as to be floated from the ground potential or set to a potential close to the plasma potential used during sputtering.

Subsequently, heat treatment is performed at 750 ° C. for 30 minutes in an N ₂ atmosphere to form a TiSi ₂ film 49 (FIG. 4C). After that, TiN films 48a and 48c, Ti film 48b
'And unreacted Ti 47a are removed, an interlayer insulating film and wirings for source / drain electrodes are formed in the same manner as in the above-described embodiment, and the MOSFET by the manufacturing method of this embodiment is completed (FIG. 4 (d). )).

Here, the first TiN film 48a and the second TIN film 48a
As shown in FIG. 3C, the i film 48b 'is formed of the first TiN film.
Excess nitrogen (1) in the film 48a is replaced with the second Ti film layer 48b '.
Of Ti (2), that is, a composition obtained by averaging the nitrogen surplus TiN film 48a and the Ti film 48b 'is formed so as to match the normal composition.

As a result of evaluating the specific resistance of the TiSi ₂ film 49, about 16 μΩcm was obtained as in the case of the first and second embodiments.
It was confirmed that the film was almost in agreement with the ideal value of.
Further, the interface just after the deposition of the Ti / TiN film thus formed and the TiSi ₂ film 49 / TiN film 4 after the heat treatment are performed.
As a result of observing the interface of No. 8 with a cross-sectional TEM, the interface using the conventional technique was unclear because a region containing a high concentration of nitrogen was formed on the TiSi ₂ surface. The Ti / TiN film interface formed by the above method and the TiSi ₂ film 49 / TiN film 48 interface after the heat treatment were very steep. The surface of the TiSi ₂ film 49 formed by the method of this example was smooth. Furthermore, it was confirmed that the heat resistance to agglomeration is improved by 50 ° C. or more as compared with the prior art as in the case of the first and second embodiment methods.

The Ti film 48 described in the above embodiment is used.
The deposition of b ′ is not limited to Ar, but the same effect can be obtained by introducing a gas that does not contain nitrogen and is inert to Ti into the sputtering chamber and perform sputtering.

Next, a fourth embodiment of the present invention will be described with reference to FIG. First, 800 n is formed on the n-type silicon substrate 11 whose main surface is (001) by an embedding method.
m field oxide film 12 is formed. A 10 nm oxide film, a 150 nm doped polycrystalline silicon layer, and a 150 nm tungsten silicide (WSi ₂ ) layer are sequentially deposited in an element region surrounded by this oxide film, and then these are processed into a gate shape by etching. Forming the tongue 13; After that, a SiN film is deposited to a thickness of 150 nm and then processed by anisotropic etching to form a SiN film 13e on the side wall of the gate. Next, a 10 nm SiO ₂ film 16 is formed on the exposed Si surface, and BF ²⁺ ions are applied at 5 × 1 at 35 keV.
0 ¹⁵ cm ^-2 was implanted to form a shallow p ⁺ diffusion layer 14 of about 0.1μm by the heat treatment of 1000 ° C. · 20 seconds in an N ₂ atmosphere (Figure 1 (a)).

Next, using a sputtering apparatus as shown in FIG. 2A, the substrate 11 to be processed and the Ti target 20 are arranged so as to face each other, and the surface of the Ti target 20 is 30 to 45 scc.
By sputtering with a plasma created by Ar gas in the range of m or other inert gas, FIG.
As shown in (b), the surface of the p ⁺ diffusion layer 14 has a thickness of 15 n.
m Ti film 17 is deposited.

Then, using a sputtering apparatus as shown in FIG. 2B, the first ionization energy of N ₂ gas of 14.
It has an ionization energy lower than 534 eV and does not chemically react with the Ti target 20.
A gas inert to the target, such as Kr (1
A mixed gas of 3.999 eV), Xe (12.130 eV) and N ₂ is introduced into the sputtering chamber. By sputtering with plasma generated by this mixed gas, a nitriding reaction is caused on the surface of the Ti target 20 to form TiN, while TiN is formed on the surface of the Ti film 17 described above.
The film 18 is deposited to a thickness of about 100 nm (Fig. 1
(B)). Here, the partial pressure ratio, the flow rate, etc. of the mixed gas used for sputtering are adjusted so that the TiN film 48 formed by sputtering has a normal composition ratio in the entire film. For example, the flow rate of N ₂ is about 20 sccm, X
The flow rate of e and Kr is about 20 sccm. Also, Ti
In the vicinity of the interface between the film 17 and the TiN film 18, the TiN film 1
The partial pressure ratio is adjusted so that 8 contains more nitrogen than the normal composition ratio.

Here, in these sputtering steps, the pressure applied to the mixed gas is set within the range of 10 ⁻³ to 10 ⁻⁴ Torr, and the substrate 11 to be processed is floated from the ground potential or used for sputtering. The positive potential is set so that the potential is close to the plasma potential.

Thereafter, as shown in FIG. 1D, the substrate 1
1 is heat-treated in an N ₂ atmosphere at 750 ° C. for 30 minutes to form a TiSi ₂ film 19. After this, TiN film 1
8 and the unreacted Ti 17 are removed, and the interlayer insulating film 10 and the wiring 10 for the source / drain electrode are formed in the same manner as in the above-mentioned embodiment.
0 is formed to complete the MOSFET by the manufacturing method of this embodiment.

As a result of evaluating the specific resistance of this TiSi ₂ film, it was confirmed that it was a film that almost matched the ideal value of about 16 μΩcm, as in the case of the previous embodiment. Further, as a result of observing the interface immediately after the deposition of the Ti / TiN film thus formed and the interface of the TiSi ₂ film 19 / TiN film 18 after the heat treatment with a cross-section TEM, as shown in FIG.
TiN interface and TiSi ₂ film 19 / TiN after heat treatment
The interface of membrane 18 was very steep. The surface of the TiSi ₂ film 19 formed by the method of the present invention was very smooth. Furthermore, the onset temperature of aggregation is kept low,
It was also confirmed that the heat resistance to agglomeration was improved by 50 ° C. or more as compared with the prior art, as in the case of the above examples.

The improvement of the TiSi ₂ film quality 19 in this embodiment is considered as follows. In the conventional sputtering using the mixture of N ₂ / Ar gas, Ar gas having a high ionization efficiency is ionized, and the energy required for the ionization (first ionization energy 15.759 eV) is higher than that of N ₂ , so that Ar emits energy. It promotes the plasma conversion (Penning ionization) of N ₂ gas in the form of being delivered. In addition, the energy difference when exciting the nitrogen plasma increases the kinetic energy of the nitrogen plasma species. Therefore, the plasma density is increased as compared with the plasma generated by only N ₂ gas, the amount of nitrogen having active high kinetic energy is increased, and more nitrogen is taken into the Ti film. Further, the substrate is in a floating state in order to prevent destruction of the gate insulating film, and the substrate is more negatively charged than in the plasma, so that positive ions are easily implanted. Here, in the plasma created by the mixed gas of N ₂ and Ar, since the plasma density is increased, the number of positive ion species is increased and T
The infiltration of nitrogen into the i film increases. In addition, since the nitrogen partial pressure is low, the mean free path of nitrogen plasma species is lengthened and the probability of reaching the Ti film is increased.

On the other hand, when the method of the present invention is used, a gas inert to Ti having a high ionization efficiency but a low first ionization energy, for example, a mixed gas of Kr, Xe and N ₂ is used to introduce the introduced gas. N in the ionization process of
The ionization of the ₂ gases themselves becomes dominant, and N ₂ ^{+ is} generated by Penning ionization of N ₂ as in the case of sputtering with plasma created by introducing only nitrogen gas into the chamber.
It is possible to prevent an increase in the plasma density, and it is possible to prevent the density of plasma from increasing. Further, the composition ratio of the TiN film 18 can be set to a desired value by adjusting the partial pressure ratio of Kr or Xe mixed with N ₂ . Moreover, since the sputtering yield of Ti is lower than that of Ar, reverse sputtering of the Ti film 17 is also unlikely to occur. Therefore, the nitrogen composition at the interface of the Ti / TiN film can be formed steeply, and a film having a normal composition containing no excess nitrogen in the TiN film 18 can be obtained. As a result, the flatness of the surface of the TiSi ₂ film 19 obtained by the heat treatment can be improved, and since the impurity nitrogen is not taken into the film, the specific resistance is reduced, and the TiN film 1
Since there is no diffusion of excess nitrogen from the inside of
The iSi ₂ film 19 can be obtained.

Although Xe and Kr are increased in this embodiment, the gas is not limited to a general inert gas as long as the gas is inert to Ti and lower than the ionization energy of nitrogen.

Further, CO may be used in addition to N ₂ gas, and in this case, it is used as a gas for mixing Kr and Xe. Further, CH ₄ can be used, and the same effect as above can be obtained by using Xe as the gas to be mixed.

Further, a fifth embodiment of the present invention will be described below with reference to FIG. First, an 800 nm field oxide film 42 is formed by an embedding method on an n-type silicon substrate 41 whose main surface is (001). In the element region surrounded by this oxide film, a 10 nm oxide film, a 150 nm doped polycrystalline layer, and a 150 nm tungsten silicide (WSi) film are formed.
₂ ) After sequentially depositing layers, this is etched into a gate shape. After that, a SiN film is deposited to a thickness of 150 nm and processed by anisotropic etching to form SiN on the side wall of the gate.
The film 43e is formed. Next, a 10 nm SiO ₂ film 46 is formed.
/ 43d is formed on the exposed Si surface, BF ²⁺ ions are implanted at 35 keV at 5 × 10 ¹⁵ cm ^-2 , and a heat treatment is performed at 1000 ° C. for 20 seconds in an N ₂ atmosphere to obtain about 0.2.
A shallow p ⁺ diffusion layer 44 of 1 μm is formed. (Fig. 4
(A)).

After that, the surface of the p ⁺ diffusion layer 44 is treated with carbon (C) -based surface contamination with a mixed solution of sulfuric acid and hydrogen peroxide, and then metal-based contamination is treated with a mixed solution of hydrochloric acid and hydrogen peroxide. To do. After that, the thin SiO ₂ film formed on the surface of the p ⁺ diffusion layer 44 is washed off with diluted hydrofluoric acid and the dissolved oxygen concentration is reduced to 1
Wash with running water with ultrapure water of 0 ppb or less.

Next, using a sputtering apparatus as shown in FIG. 2A, the substrate 41 to be processed and the Ti target 20 are arranged to face each other, and the surface of the Ti target 20 has a flow rate of 30-4.
A thickness of 1 is formed on the surface of the p ⁺ diffusion layer by sputtering with plasma generated by Ar gas in the range of 5 sccm.
An 8 nm Ti film 47 is deposited. Then, using a sputtering apparatus as shown in FIG. 2B, Ar, N ₂ and C ₂
The Ti target 20 is sputtered by plasma generated by a mixed gas of H ₄ , and TiN is formed by the nitriding reaction of the surface of the Ti target 20, while the first Ti—C—N film is first formed on the surface of the Ti film 47. 48a ″ is deposited to a thickness of about 10 nm so that the nitrogen composition is higher than the normal composition ratio. Here, the flow rate of Ar is about 20 sccm, and N is about 20 sccm.
The flow rate of ₂ is 20 sccm and the flow rate of C ₂ H ₄ is 5 sc
It is set to about cm and introduced into the chamber.

Next, the Ti target 20 is sputtered by the plasma of the mixed gas of N ₂ , C ₂ H ₄ and Ar, the partial pressure ratio of which is adjusted so that the composition of nitrogen is smaller than the normal composition, so that the first Ti is sputtered. A second Ti—C—N film 48b ″ is deposited on the surface of the —C—N film 48a ″ to a thickness of about 5 nm. Finally, the partial pressure ratio is adjusted so that the composition of the formed film 48c has a stoichiometric composition ratio of 1: 1.
By sputtering the surface of the Ti target 20 with plasma of a mixed gas of ₂ and Ar, a nitriding reaction is caused on the surface of the Ti target 20 to form TiN, and the surface of the second Ti—C—N film 48b ″ is formed. TiN film 4
8c is deposited to a thickness of about 60 nm. (Fig. 4 (b))
In these sputtering steps, the pressure applied to the mixed gas is set in the range of 10 ⁻³ to 10 ⁻⁴ Torr, and the substrate 41 to be processed is set.
Is placed at a positive potential so as to be floated from the ground potential or close to the plasma potential used in sputtering.

After that, as shown in FIG. 4C, the substrate is heat-treated at 750 ° C. for 30 minutes in an N ₂ atmosphere, and T
The iSi ₂ film 49 is formed. Finally, as shown in FIG. 4D, the Ti—C—N film 48a “48b”, the unreacted TiN film 48c, and the unreacted Ti 47a are removed, and the interlayer insulating film 10 and the source are formed in the same manner as in the above-described embodiment. -By forming the wiring 100 for the drain electrode, the MOSFET by the manufacturing method of this embodiment is completed.

As a result of evaluating the specific resistance of this TiSi ₂ film 49, it was confirmed that it was a film which almost matched the ideal value of about 16 μΩcm, as in the case of the above-mentioned embodiment. Also,
Thus after the interface and the heat treatment immediately after the formation were Ti / Ti-C-N films deposited TiSi ₂ film 49 / Ti-C-
As a result of observing the interface of the N film 48a ″ with a cross-sectional TEM,
/ Ti-CN film 48a "interface and TiS after heat treatment
The i ₂ film / Ti—C—N film interface was very steep. The surface of the silicide formed by the method of the present invention was smooth. Further, it was confirmed that the heat resistance against agglomeration is improved by 50 ° C. or more as compared with the prior art as in each of the above examples.

This improvement in the film quality is that the Ti / Ti-C-N film interface can be formed steeply as already shown in the second embodiment, and the excess C and N Ti film side in the cap film at the time of heat treatment. To prevent re-diffusion to. Further, the cap film containing C has an effect of closing the grain boundary in the TiN cap film, and impurities are passed through the cap film to prevent the Ti film 47 from having impurities.
It can be prevented from spreading to the side.

C ₂ H used as a mixed gas with N _2
In addition to ₄ , the same effect can be obtained by using a hydrocarbon gas such as CH ₄ , C ₂ H ₂ and C ₂ H ₆ , and when O ₂ and CO are used, oxygen and carbon A film containing is obtained.

Next, a sixth embodiment of the present invention will be described with reference to FIG. First, an 800 nm field oxide film 42 is formed by an embedding method on an n-type silicon substrate 41 whose main surface is (001). A 10 nm gate oxide film, a 150 nm doped polycrystalline silicon layer, and a 150 nm tungsten silicide (WSi ₂ ) layer are sequentially deposited in an element region surrounded by this oxide film, and then these are processed into a gate shape by etching. After this, the SiN film is 150 nm thick.
And then processed by anisotropic etching to form a SiN film 43e on the side wall of the gate 43. Next 10
nm SiO ₂ film 46 is formed on the exposed Si surface and then BF
²⁺ ions are implanted at 35 keV at 5 × 10 ¹⁵ cm ^-2 , and N _{2 is} injected.
A shallow p ⁺ diffusion layer 44 of about 0.1 μm was formed by applying a heat treatment at 1000 ° C. for 20 seconds in the atmosphere (FIG. 4A).

After that, the surface of the p ⁺ diffusion layer 44 is treated with carbon (C) -based surface contamination with a mixed solution of sulfuric acid and hydrogen peroxide, and then metal-based contamination is treated with a mixed solution of hydrochloric acid and hydrogen peroxide. To do. After that, the thin SiO ₂ film formed on the surface of the p ⁺ diffusion layer 44 is washed off with diluted hydrofluoric acid and the dissolved oxygen concentration is reduced to 1
Wash with running water with ultrapure water of 0 ppb or less.

Next, a Ti film 47 and a TiN film 48 are formed by using a parallel plate type plasma CVD apparatus as shown in FIG.
a, b, c are formed. In FIG. 6, the chamber 61
The gas inside is exhausted by the pump, and the reactive gas is introduced into the chamber 61 from the shower head 64. Inside the chamber 61, flat plate type electrodes 64 and 66 are installed in parallel with each other. A high frequency power source 67 is installed on the electrode 64 via a matching box 68, and the electrode 6
A substrate 41 to be processed (here, a silicon substrate 41 which has undergone the above-described process) is placed on the substrate 6.

First, as the source gas, titanium tetrachloride (TiC) having a flow rate of about 5 sccm from the gas inlet 63 is used.
l ₄ ) gas and hydrogen (H ₂ ) gas having a flow rate in the range of 10 to 20 sccm while introducing 10 ⁻³ torr in the reaction vessel.
Keep around r. Here, an AC wave having a frequency of 13.56 MHz generated from the high frequency power source 67 is applied to the upper power source 64 by 20
A discharge is caused by applying the power of 0 W.

The introduced reaction gas is ejected from a plurality of holes provided in the upper power source and is activated by the energy of the discharge, thereby causing a chemical reaction, and the substrate 6 to be processed.
No. 5 p ⁺ diffusion layer 44 surface 18 nm thick Ti film 47
Are deposited (FIG. 4B).

Subsequently, titanium tetrachloride (TiCl ₄ ) gas whose flow rate is set to, for example, 5 sccm and nitrogen gas whose flow rate is set to a range of 20 to 100 sccm are provided in the chamber so that the composition of the TiN film 48a with excess nitrogen is obtained. And 10
The inside of the reaction vessel is maintained at about 10 ⁻³ torr while introducing hydrogen gas set in the range of ˜19 sccm. here,
A discharge is generated as described above. In this way, the first TiN film 48a is first deposited on the surface of the Ti film 47 to a thickness of about 10 nm (FIG. 4B).

Next, a titanium tetrachloride (TiCl ₄ ) gas having a gas flow rate set in the range of 0.1 to 1.0 sccm so that the composition of nitrogen is smaller than the normal composition, and 10 to 10
Nitrogen (N ₂ ) gas set in the range of 30 sccm and 40
The mixed gas with hydrogen gas set in the range of -60 sccm is discharged in the same manner as above, and the second TiN film 48b is deposited on the surface of the first TiN film 48a to a thickness of about 5 nm (Fig. 4 (b )).

Finally, the composition of the TiN film formed is 1: 1.
Titanium tetrachloride (TiCl ₄ ) gas and ammonia (NH ₃ ) with the gas flow rate adjusted so that the stoichiometric composition ratio of
The mixed gas of gases is discharged, and the third TiN film 48c is deposited on the surface of the second TiN film 48b to a thickness of about 60 nm (FIG. 4B). Here, the total flow rate of the mixed gas is 4
The flow rate of TiCl ₄ is set in the range of 0.1 to 1.0 sccm. Further, in these plasma CVD processes, the substrate 41 to be processed is arranged so as to be floated from the ground potential or to be able to apply a positive bias to the substrate side so as to have the same potential as the plasma potential.

Then, heat treatment is performed at 750 ° C. for 30 minutes in an N ₂ atmosphere to form a TiSi ₂ film 49 (FIG. 4C). Then, the TiN films 48a, 48b, 48c and unreacted Ti are removed to selectively form silicide (FIG. 4).
(D)).

As a result of evaluating the specific resistance of the TiSi ₂ film 49, it was confirmed that it was a film that almost matched the ideal value of about 16 μΩcm, as in the case of the above-mentioned embodiment. In addition, the Ti film 47 / TiN film 48 thus formed
The interface immediately after the deposition of a and the TiSi ₂ film 49 /
As a result of observing the interface of the TiN film 48a with a cross-sectional TEM, the Ti film 47 / TiN film 48a formed by the method of the present embodiment.
Interface and TiSi ₂ film 49 / TiN film 4 after heat treatment
The interface of 8a was very steep. The surface of the silicide formed by the method of the present invention was smooth. Furthermore,
It was also confirmed that the heat resistance to agglomeration was improved by 50 ° C. or more as compared with the conventional technique, as in the case of the method of the above-mentioned embodiment.

The same effect can be obtained by introducing only nitrogen gas and exposing the surface of the Ti film 47 to nitrogen plasma only for the nitrogen-excess first TiN film 48a in the above embodiment. Further, although TiCl ₄ gas is used as the gas containing Ti in this embodiment, another gas containing Ti may be used. For example, Ti [N (C ₂ H ₅ ) ₂ ] ₄ , Ti [N (CH ₃ ).
₂ ] ₄ gas or the like, an organic compound gas of Ti, and a gas such as a halogenated Ti gas can be used.

Ammonia (NH ₃ ) may be used instead of the mixed gas of nitrogen and hydrogen. Further, as shown in FIG. 3B, the relationship between the composition and film thickness of the first TiN film 48a and the second TiN film 48b as in the above embodiment is as follows.
Excess nitrogen (1) in the first TiN film 48a is replaced with second Ti
Excess Ti (2) in the N film 48b can be consumed, that is, the nitrogen-excess first TiN film 48a and the Ti-excess second T
The average composition of the iN film 48b is configured to match the normal composition. Similarly, the second TiN film 48 is also formed.
Even when b is the Ti film 48b ', the first TiN film 48a and the second Ti film 48b' can remove the excess nitrogen in the first TiN film from the second TiN film 48b 'as shown in FIG. Ti film 48b
'Ti can be consumed by Ti, that is, nitrogen surplus first
The composition obtained by averaging the TiN film 48a and the Ti surplus second Ti film 48b 'is configured to match the normal composition.

In the above embodiments, when the TiN films 18 and 48 are deposited, if the sputtering is performed while heating the substrate at 100 to 300 ° C., the TiN film does not react with the TiN film and TiN film does not react. Since the lattice defects and the like in the film are recovered and the crystallinity is improved, surplus nitrogen is less likely to be taken in, and a further effect is obtained.

Further, in the method described in each of the above embodiments, T
The i / TiN film was formed TiSi ₂ film 19, 49 by heat treatment in a nitrogen atmosphere, but the annealing Ar
Further effects were obtained when performed in an atmosphere. This is because in the conventional heat treatment method in a nitrogen atmosphere, nitrogen reaches the surface of the Ti film through the grain boundaries of the TiN columnar crystals from the heat treatment atmosphere, promotes nitriding, and takes in nitrogen at the time of silicide formation to obtain TiSi ₂ Since the morphology of the film surface is deteriorated, the film quality deteriorates as shown in the first embodiment. By heat treatment in an Ar gas atmosphere, the film quality is improved because there is no influence of nitrogen from the atmosphere, not only is easy control of the film thickness even in the thin film formation, not TiSi ₂ film only, TiN Since nitrogen is not taken into the crystal grain boundaries, heat resistance against agglomeration is further improved. . Furthermore, even when TiN is composed of a composition containing a large amount of nitrogen,
Since the annealing atmosphere does not contain nitrogen, nitrogen diffuses outward into the Ar atmosphere, so that the diffusion of nitrogen into the Ti film can be minimized.

Needless to say, the present invention is not limited to the above-mentioned embodiment, but can be modified in various ways. For example, in addition to the TiN film / TiSi ₂ film shown in this embodiment, a TiN film / NiSi _x film, a TiN film / CoSi _x film
Film (x = 0.5,1,2), TiN film / Pd _x Si film, TiN film / ZrSi _x film, ZrN / ZrSi _x film, TiN film / W
Si _x film, W ₂ N film / WSi _x film, TiN film / TaSi
_x film, TaN film / TaSi _x film, TiN film / HfSi _x
Film, is also applicable to HfN film / HfSi _x film. That is, when forming another metal silicide, a compound film to be formed as a cap layer is deposited and formed on each metal film to prevent impurities from penetrating into the formed interface and diffusion of impurities from the compound film layer. By doing so, the same effect can be expected.

The cap layer is not limited to the TiN film, and the same applies to combinations of various silicides with a TiN film containing oxygen or carbon as an impurity, a carbide film, a boride film, or another compound film. Discussion is possible. Regarding the heat treatment atmosphere, if it is an inert heat treatment atmosphere in which the partial pressure of nitrogen is lowered, or an atmosphere that does not contain not only the inert gas but also the substance forming the cap and does not react with the deposited laminated film, It is possible to obtain the same effect as that of the embodiment. Further, in the above embodiment,
In each of the cases, the case where the compound film cap is peeled off has been described, but the present invention is not limited to this, and it is also applicable to a structure in which the compound film is not peeled off. For example, it can be applied to the case of a TiN film which is a compound film used as a barrier metal of wiring used for embedding a blanket W or the like.

Further, in the above embodiment, the description was made on the p ⁺ -Si substrate, but the same technique can be applied to the n ⁺ -Si substrate, and the SOI (Semiconductor On Ins) which has been widely used as a semiconductor substrate in recent years.
ultor) structure can be used, and the above-described technique can be applied to the semiconductor layer on the insulating layer.

Further, the present invention can be effectively applied when the thickness of the first film made of a transition metal, particularly the film made of titanium, is 20 nm or less, particularly 10 to 20 nm. In addition, various modifications can be made without departing from the scope of the present invention.

[0107]

According to the present invention, a metal silicide thin film having uniform film quality, low specific resistance and good heat resistance can be formed on a substrate, and a highly reliable metal compound film is realized on a shallow junction. be able to.

[Brief description of drawings]

FIG. 1 is a process sectional view showing a method for manufacturing a MOSFET, which is a first and a fourth embodiment of a method for manufacturing a semiconductor device according to the present invention.

FIG. 2 is a schematic diagram showing a sputtering apparatus used in the manufacturing method of each example of the present invention.

FIG. 3 shows Ti obtained by the manufacturing method of each example of the present invention.
The figure which shows the composition of N film / Ti film.

FIG. 4 is a MOSFET according to second, third, fifth and sixth embodiments of the method of manufacturing a semiconductor device according to the present invention.
Process cross-sectional views showing the manufacturing method of.

FIG. 5 is a diagram showing the composition of a TiN film / Ti film obtained by the manufacturing method according to the fourth embodiment of the present invention.

FIG. 6 is a schematic diagram showing a plasma CVD apparatus used in a manufacturing method according to a sixth embodiment of the present invention.

FIG. 7 is a process cross-sectional view for explaining a conventional technique of the present invention.

[Explanation of symbols]

11, 41 Silicon substrate 12, 42 Field oxide film 13, 43 Gate part 14, 44 p ⁺ diffusion layer 17, 47 Ti film 18, 48 TiN film 19, 49 TiSi ₂ film 10 Inter-layer insulating film film 100 Electrode wiring layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H01L 29/78 H01L 29/78 301 G

Claims (13)

[Claims] 1. A step of forming a first film of a transition metal on the surface of a semiconductor substrate, and a second step of forming a compound of the transition metal and a second periodic element of the periodic table on the surface of the first film. Forming a film containing the second periodic element larger than the normal composition in a region in contact with the first film, and forming the film on the surface of the semiconductor substrate by heat treatment and the first element. And a step of forming a third film made of a compound of the above film with a transition metal. 2. The second film is formed by containing the second periodic element in an amount less than the regular composition on the surface side of a region in which the second periodic element is contained in an amount larger than the regular composition. The method for manufacturing a semiconductor device according to claim 1. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the second film is formed by including the second periodic element in a regular composition on the surface thereof. 4. The method for manufacturing a semiconductor device according to claim 1, wherein a composition obtained by averaging the inside of the second film is a normal composition. 5. The step of forming the second film is a step of forming a transition metal of the second film in an atmosphere of a gas containing the second periodic element as a main component in an initial stage of film formation. The method for manufacturing a semiconductor device according to claim 1, wherein the method is performed by sputtering the get. 6. The step of forming the second film, after the initial stage of the film formation, in the gas atmosphere containing the second periodic element in a smaller amount than in the initial stage of the film formation, 6. The method of manufacturing a semiconductor device according to claim 5, wherein the target is made of a transition metal of the film of No. 2 by sputtering. 7. A first film made of a transition metal is formed on the surface of a semiconductor substrate by sputtering a target made of the transition metal in an atmosphere of an inert gas inert to the transition metal. A step of forming a second film made of a compound of a transition metal and a second periodic element of the periodic table on the surface of the first film, a gas containing the second periodic element, and a first ionization than the gas. It is formed by sputtering a target made of the transition metal of the second film in an atmosphere of a mixed gas having low energy and an inert gas inert to the transition metal of the first film. And a step of forming a third film made of a compound of a constituent element of the semiconductor substrate and a transition metal of the first film on the surface of the semiconductor substrate by heat treatment. Made of Build method. 8. The gas containing the second period element is N ₂ , and the inert gas having a first ionization energy lower than that of the gas is at least one of xenon and krypton. 7. The method for manufacturing a semiconductor device according to 7. 9. An insulating film having a desired pattern is formed on the semiconductor substrate, and then the first and second insulating films are formed on the semiconductor substrate.
8. The semiconductor device according to claim 1, wherein the third film is formed in a self-aligned manner by heat treatment on the surface of the semiconductor substrate other than the region where the insulating film is formed. Manufacturing method. 10. The impurity diffusion layer is formed on the surface of the semiconductor substrate, and the third film is formed on the surface of the semiconductor substrate on which the impurity diffusion layer is formed. 7. The method for manufacturing a semiconductor device according to 7. 11. The method of manufacturing a semiconductor device according to claim 1, wherein the second periodic element is any one kind or plural kinds of elements of B, C, N, and O. 12. The transition metal of the first and second films is T.
8. The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is i. 13. The method of manufacturing a semiconductor device according to claim 1, wherein the third film is made of a transition metal silicide and has a film thickness of 50 nm or less.